Protective device for incandescent lamps



C. A. B. HALVORSON, In, PROTECTlVE DEVICE FORTNCANDESCENT LAMPS.

APPLICATION Huu' ocr. 26,1916.

PatentedMay 24 1921i.

25 IT) vencor:

Cromwell $1.13. Hal VOTSOT) J17,

His ttomeg.

warren stares HUSETTS, ASSIGNOR 1'0 GENERAL ELECTRIC COMEANY, ACORPORATION 03 NEVJ YQRK.

PROTECTIVE DEVICE FOR INCANDESCENT LAMIPS.

awrence.

Application filed October 26, 1916.

To all whom it may concern:

Be it known that T, CRoMwELL A. B. HAL- VORSON, J11, a citizen of theUnited States, residing at Lynn, county of Essex, State oflllassachusetts, have invented certain new and useful Improvements inProtective Devices for Incandescent Lamps, of which the following is aspecification.

My present invention relates to protective devices and cut-outs forincandescent lamps, and more particularly for use with such lamps whenoperated on direct current series circuits.

When incandescent lamps are operated on series circuits, in case thefilament of one lamp on the circuit burns out or becomes broken or forany reason duringthe operation of the lamp there is a tendency for anarc to rorm which may assume such proportions as to cause the lamp toexplode, or in case the lamp is burned with the tip downward it may movealong the leading-in wires and cause fusing oi' the lamp socket. As soonas the arc becomes extinguished, unless the lamp is short-circuited, thecontinuity of the circuit is broken and all of the lamps on the circuitbecome dead.

The object of my invention is to overcome the above difficulties andprovide a device whereby the continuity of the circuit will not bebroken when the filament of any lamp on the circuit becomes broken forany reason. A further object of my invention is to provide a devicewhich will offer protection to the lamp from abnormal conditionsoccurring in the circuit to which it is connected.

In carrying my invention into effect I provide one of my improveddevices for each lamp on the circuit. The device in its generalcharacteristics comprises a coil which is in series with the lamp and asecond coil which is in shunt to the lamp. A resistance is also providedwhich is in shunt to the lamp when the lamp is not burning. W hen thecurrent starts to flow in the circuit the series coil operates a contactto open-circuit the resistance so that the main current will all flowthrough the lamp except for a small amount carried by the shunt coil. Incase the filament of the lamp becomes broken the momentary rise involtage across the lamp is suilicient to cause the shunt coil to operateand close a contact which throws the resistance in shunt to the lamp andallows the main current to flow through the resistance.

Specification of Letters Fatent.

Patented May 24:, 1921. Serial no. 127,812.

ds soon as this occurs the potential across the lamp 1s decreased andany are which may be Iormed in the lamp is extinguished. as soon as thecurrent through the lamp is interrup ed the contact operated by theseries coil again closes the circuit throu h the shunt resistance. b

The features of my invention which I consider novel are polntedout withparticun the appended claims, the invention itseir, however, both as toits mode of operatlon and organization will best be understood byreference to the following description taken in connection with theaccompanying drawing in which Figure l is a view partly in section andpartly in elevat on of one or my devices; Fig. 2 is a plan view of thesame; F 3 is an elevation of thpOltlOl'l or the device as seen from lineXXpr" Fig. l; Fig. l is a plan view of a portion of the device as seenalong the line TY of Fig. l; and 5 is a diagram showmg the method oiconnecting my device to a lamp.

{as shown in the drawing my device comprises a series coil 1 and a shuntcoil 2 supported by a frame-work 3. The core d of the series coilcarries at its lower end a contact member 5. l v hen the lamp is not inoperation the contact 5 rests upon a stationary contact member 6 whichis supported from the frame-work 3 by means of a bracket 7 fastened tothe frame-work b means of the screws 8. The contact 6 is held directlyby a clamp 9 which is supported from the bracket '7 but insulatedtherefrom by means of the insulating members The core ll of the shuntcoil 2 acts upon the pivoted armature 12 which carries the contactmember 13. A resistance 1% has one erminal connected to the lampterminal 15 and the other terminal is connected to the stationarycontact member 6 by means of binding post 16 which is fastened to theclamp 9 The normal position of the different parts when the lamp is notin operation is indicated diagrammatically in Fig. 5. It will be seenthat there are two paths through the device through which current fromthe line conductors 17 and 17 may flow. One of these paths is throughthe lamp 18 and the series coil 1, the other through resistance 14,contact members 6 and contact member 5. There is in addition a shuntpath through the shunt C011 2.

, to cause this coil to operate and attract its.

When current starts to flow through the line conductors 17, 17, thecurrent will divide, part of it going through the lamp and series coil,part through the resistance 14: and a very small amount through theshunt coil 2. Thereupon the series coil 1 will operate and cause contactmembers 5' and 6 to separate, thereby cutting out resistance 141 andcausing the main current to flow through the lamp. The shunt coil 2 isso proportioned and its core 11 so adjusted that it will not attract thearmature 12 unless the potential across the coil is somewhat greaterthan the normal operating voltage of thelamp. It now the filament of thelamp should become ruptured there would be a momentary rise in voltageacross the lamp terminals and across coil 2 suificient armature, thuscausing contact 13 to close upon contact 6 again connecting theresistance in shunt to the lamp. As soon as this happens the potentialacross the lamp will fall, the value of resistance 14: being much lessthan the normal resistance of the lamp. Thus any arc which might form inthe lamp will at once be extinguished and the current through the lampinterrupted. As a result core 41 will be released allowing contacts 5and 6 to come together and thus furnish a path for current through theresistance, at the same time that armature 12 is released by reason ofthe drop in voltage at the terminals of coil 2.

In order to render the device suitable for operation with lamps havingdifferent voltage ratings, I have provided a special means for adjustingthe core of the shunt coil 2 whereby the device may be quickly adaptedto be used with lamps of different voltages. The upper end of the core 2is provided with screw threads and is held in place by means of a nut 19which is furnished with an indicating pointer 20. The initial adjustmentof the device may be carried out by means of the nut 19 and also bymeans of the screw stop 21 by which the position of the armature 12 maybe determined. f the adjustment is made so that the device operatesproperly with lamps of normal operating voltage it may be so arrangedthat the pointer 20 is turned for example to the scale marking 22, thenif the particular lamp which is to be used with the device happens tohave a voltage rating slightly above or below the normal operatingvoltage, by turning the nut 19 to the right or left toward scalemarkings 23 or 24:, the device may be quickly adjusted so that itsoperation will be correct for the particular lamp which is to be used.When the proper adjustment has once been made the core may be held inposition by tightening the thumb nut 25; It will of course be understoodthat the scale markings 22, 23 and 2 1 may be given any convenientdesignation to enable the one who changes the lamps to readily tell at aglance the exact point to which the pointer 20 should be moved, it beingassumed that the lamp which is placed'in the fixture is marked with itsproper voltage rating.

If for any reason there should be a rise in current in the circuit abovethe normal operating current the voltage across the shunt coil will riseand cause it to close the contact 13 upon contact 6, thus allowing themain current to flow through the resistance and thus protect the lampfrom burning out.

While I have illustrated a single embodiment of my invention, it will beapparent that many modifications in the structural details as well as inthe exact method of connection, may be made without departing from thescope o1 my invention as set forth in the'appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. The combination with an incandescent lamp of a coil in seriestherewith, a coil in shunt to said lamp and said series coil, aresistance, a movable contact member operated by each of said coils anda stationary contact member which cooperates with both of the movablecontact members to throw the resistance in shunt to the lamp and theseries coil, the parts being so arranged and proportioned that in thenormal operation of the lamp both movable contact members will be out ofcontact with the stationary contact member, when the lamp is opencircuited the member operated by the series coil will be in contact withthe stationary member and when the voltage across the lamp rises above apredetermined value the member operated by the shunt coil will be incontact with the stationary member.

2. The combination with an incandescent lamp of a coil in seriestherewith, a coil in shunt to the lamp and the series coil, a movablecontact member operated by each of said coils, and a resistance theparts being so arranged and proportioned that when the lamp is not inoperation the resistance will be in shunt with the lamp and the seriescoil, when current starts to flow in the lamp the resistance wil be opencircuited by the contact member operated by the series coil, and whenthevoltage across the lamp rises above a predetermined value the resistancewill be thrown in shunt with the larfip and the series coil by thecontact member operated by the shunt coil.

3. The combination with an incandescent lamp of a coil in seriestherewith, a coil in shunt to the lamp and'the'series coil, a resistanceand contact members controlled by said coils, the parts being soproportioned and arranged that when the lamp is'not in operation theresistance will be in shunt to the lamp and the series coil during thenormal operation of the lamp the resistance will be open circuited andwhen the voltage across the lamp exceeds a predetermined value theresistance will be thrown in shunt with the lamp and the series coil.

4. A protective device for incandescent lamps comprising a coil adaptedto be connected in series with a lamp, a coil adapted to be connected inshunt to the lamp and the series coil, a resistance, a movable contactmember operated by each of said coils, and a stationary contact memberwhich cooperates with both of said movable contact members the partsbeing so arranged and proportioned that when the series coil alone isenergized both movable members will be out of contact with thestationary member, when the shunt coil alone is energized both movablemembers will be in contact with the stationary member, and when bothcoils are energized the movable member controlled by the shunt coil willbe in contact with the stationary member, and the other movable memberwill be out of contact with the stationary member, and when eithermovable member is in contact with the stationary member the resistancewill be in shunt to the shunt coil.

5. A protective device for incandescent lamps comprising a coil adaptedto be connected in series with a lamp, a coil adapted to be connected inshunt to the lamp and the series coil, a. resistance adapted to beconnected in shunt to the lamp and series coil, a movable contact memberoperated by each of said coils, and a stationary contact member whichcooperates with both of said movable contact members the parts being soarranged and proportioned that when the series coil alone is energizedboth movable members will be out of contact with the stationary member,when the shunt coil alone is energized both movable members will be incontact with the stationary member, and

' when both coils are energized the movable member controlled by theshunt coil will be in contact with the stationary member, and the othermovable member will be out or" contact with the stationary member, andwhen either movable member is in contact with the stationary member theresistance will be in shunt to the shunt coil, the shunt coil being soproportioned that it will be operatively energized only when the Voltageapplied thereto exceeds a predetermined desired amount and beingprovided with means for adjusting it to operate at the desired voltage.

6. lhe combination with an incandescent lamp of a coil in seriestherewith, a coil in shunt to the lamp and the series coil, a movablecontact member operated by each of said coils, a stationary contactmember and a resistance, the parts being so arranged and proportionedthat in the normal operation of the lamp both movable contact memberswill be out of contact with the stationary contact member and theresistance open circuited, when the lamp is open circuited the memberoperated by the series coil will be in contact with the stationarymember and the resistance in circuit and when the voltage across thelamp rises above a predetermined value the member operated by the shuntcoil will be in contact with the stationary member and the resistance incircuit.

7. The combination with an incandescent lamp of a coil in seriestherewith, a coil in shunt to the lamp and the series coil, a movablecontact member operated by each of said coils, a stationary contactmember and a resistance having one terminal connected to said stationarycontact member and the other terminal connected to a lamp terminal, saidmovable contact members being connected to a terminal of the seriescoil, the parts being so arranged and proportioned that in the normaloperation of the lamp both movable contact members will be out ofcontact with the stationary contact member, when the lamp is opencircuited the member operated by the series coil will be in contact withthe stationary member and when the voltage across the lamp rises above apredetermined value the member operated by the shunt coil will be incontact with the stationary member.

In witness whereof, I have hereunto set my hand this 24th day ofOctober, 1916.

CROMWELL A. B. HALVORSON, Jr.

